Exhaust muffler filter



April 14, 1964 M. L. HOBBS 3,129,078

' EXHAUST MUFFLER FILTER Filed June 16. 1961 INVENTOR. HOB 5 ATTORNEYJUnited States Patent 3,129,078 EXHAUST MUFFLER FILTER Marian L. Hobbs,916 Orville, Kansas City, Kans- Filed June 16, 1961, Ser. No. 117,548 3Claims. (Cl. 55-313) This invention relates to improvements in muiflersor silencers of the type employed with internal combustion engines, andmore particularly to a muffler or silencer for use on exhaust pipes ofmotor vehicles for both silencing the explosive noises and removingsmog-forming elements from exhaust gases.

Due to the noise produced by exhaust gases from internal combustionengines being exhausted directly into the air, it is usually necessaryto provide them with devices to mufile or silence such noises. Theexhaust gases also carry impurities such as carbon particles and gaseswhich are offensive in smell and often dangerous. Under certainconditions, the exhaust gases of motor vehicles when discharged into theair introduce smog-forming elements in the air which cause anaccumulation of what is commonly called smog, particularly in largecities and substantial accumulations in the air are offensive and, inmany instances, harmful to life and property. Filters for exhaust gaswill tend to remove some smogforming elements, but obstructions in theexhaust pipes which cause back pressure on the exhaust ports of anengine will substantially reduce the power and efliciency of the engine,and it has been found that where attempts have been made to pass all ofthe exhaust gas of a motor vehicle through a filter, the carbonparticles and the like fill the voids in the filter to the point that itbecomes an obstruction with a rapid drop of efficiency in performance ofthe engine.

The principal objects of the present invention are to provide a mulflerfor connection in an exhaust pipe of an internal combustion enginewhich, in addition to silencing the exhaust noises, will removesmog-forming elements from the exhaust gases; to provide such a mufflerstructure with gas filtering elements therein and bypass passages aroundthe filtering elements whereby the engine can perform if gas flowthrough the filtering elements is obstructed; to provide such astructure wherein the bypass passages are arranged to provide slightrestriction to flow of exhaust gases therethrough to cause the principalportion of the gases to pass through the filtering element; to providesuch a mufller structure that is adapted to be installed in an exhaustpipe of a motor vehicle in place of the regular mufller without alteringthe parts of the vehicle or as a smaller size in addition to the regularmuffier; and to provide an internal combustion engine muffler that iseconomical to manufacture, that is efficient in reducing exhaust noiseand in removing smog-forming elements from the exhaust gases with aminimum of resistance or retardation of flow of exhaust gastherethrough.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings wherein are set forth by way of illustration and examplecertain embodiments of this invention.

FIG. 1 is a perspective view of a muffler embodying the features of thepresent invention.

FIG. 2 is a longitudinal sectional view through a modified form ofmufiler.

FIG. 3 is a transverse sectional view through the mufiler illustrated inFIG. 2 taken on the line 33, FIG. 2.

FIG. 4 is a longitudinal sectional View through a further modified formof muffier.

FIG. 5 is a transverse sectional view through the muffler shown in FIG.4 taken on the line 5-5, FIG. 4.

FIG. 6 is an enlarged transverse sectional view through the bypass valvein open position.

Referring more in detail to the drawings:

1 generally designates a mufiler filter structure having a tubularimperforate shell or casing 2 having end walls 3 and 4 suitably attachedthereto. In the illustrated structure, the end walls have outwardlydirected peripheral flanges 5 and the ends of the casing overlie saidflanges and are turned inwardly to underlie the flanges as at 5 and aresuitably secured thereto in a substantially gastight seal. The end walls3 and 4- each have outwardly turned flanges 7 defining a bore 8 in whichis mounted a short tubular extension with the inlet extension in the endwall 3 arranged for reception of an exhaust pipe 10, the tubular outletextension 9 in the end wall 4 being received in a tailpipe 11 Theextensions 9 and 9 are suitably secured as by welding to the flanges 7of the end walls 3 and 4 to form a gas-tight connection, and theextensions 9 and 9 are secured to the exhaust pipe 10 and tailpipe 11respectively in any suitable conven tional manner. The inner ends of theextensions 9 and 9 have annular flanges 12 and 12' respectivelyextending substantially radially therefrom and terminating in spacedrelation to the wall of the casing 2 to provide a passage therebetween.A perforate shell 13 has ends suitably secured as at 14 to theperipheral edges of the flanges 12 and 12 to define a space extendingbetween the inner ends of the extensions 9 and 9, and said space isfilled with a fibrous filtering material 15 such as a mass of glassfibers. formed of a wire mesh but may be of other perforate materialthat will retain its shape and confine the fibrous filter material.

A bypass around the filtering material 15 is provided by a plurality ofapertures 16 on the extension 9 of the end wall 3 and a plurality ofapertures 17 in the extension 9' on the end wall 4, said apertures beingbetween the annular flanges 12 and 12' and the respective end walls 3and 4, and, also, of suitable size and quantity wherein the combinedarea of the apertures 16 or the combined area of the apertures 17 equalsor is greater than the area in the exhaust pipe 10. Flow of exhaust gasthrough the apertures 16 is retarded by suitable valve members 18 whichwill open under very small pressure, the valve members being biasedtoward closing position. In the illustrated structure, the valve members18 consist of flat, leaf-like spring members curved to fit the outsidecontour of the extension 9 with one end of each of the valve memberssecured by suitable fastening device such as a rivet 19 to the extension9 and spaced circumferentially of the apertures 16. The valve members 18are biased to closing position whereby under normal operating conditionsthe valves remain closed and the exhaust gas passes into the filteringmaterial in the shell 13, but if resistance to flow of the exhaust gasesthrough the filtering material is increased, the resulting increasedpressure in the extension 9 will cause the valve members to open wherebythe exhaust gases will escape through the apertures 16 and pass throughthe space 211 between the shell 13 and the casing 2 and enter theapertures 17 for discharge through the tailpipe 11.

In using a muffler constructed and assembled as described, and with themufiler connected to an exhaust pipe 10 and tailpipe 11 as illustrated,operation of the internal combustion engine connected to the exhaustpipe 10 will direct the gases into the filter media 15 in the shell 13.Some of said exhaust gases will pass through the length of the shellinto the extension 9' on the end 'wall 4 and be discharged through thetailpipe 11. A

portion of the gas will escape radially through the filter media andthrough openings 21 in the shell whereby said In the illustratedstructure, the shell 13 is escaping gases will pass through the space 20to the apertures 17 and through the extension 9' to the tailpipe 11. Thefilter media will remove carbon particles and smogforming elements andthereby reduce the possibility of smog being formed in the area in whichthe vehicle is operated. As carbon and other elements are accumulated inthe filter media 15 sufficiently to close the spaces between the fibersand retard flow of exhaust gas therethrough, the pressure within theextension 9 on the end wall 3 will increase slightly and cause thevalves 18 to open for flow of some of the exhaust gas through theapertures 16, space 2%) and into the apertures 17, bypassing the filterelement. During this bypass of a portion of the exhaust gas, there willbe some gas passing through the filter whereby it will still beoperative to reduce the quantity of smog-forming elements therein.However, even after the filter element is completely filled to stop flowof exhaust gases therethrough, the engine will continue to operate asthe exhaust gases then will cause the valves 18 to open and bypass thefilter element, whereby the vehicle can be operated until an opportunityis obtained for replacing the muffler and filter unit.

In the form of the invention illustrated in FIG. 2, the muffier unit 22has a shell 2, end walls 3 and 4, and extensions 9, annular flanges 12on the inner ends of the extensions, and a perforate shell 13 containingfilter media 15 such as fiberglass that are substantially the samestructure and assembled in substantially the same manner as in themuffler 1 illustrated in FIG. 1. In the mufier 22,

a filter medium such as fiberglass or the like is arranged in a layer 23around the inside of the casing 2 with said filter media retained inplace by a perforate tubular member 24 which, in the illustratedstructure, is in the form of a wire mesh cylinder spaced outwardly fromthe shell 13 to provide a through space or passage 25 therebetween. Inplace of the apertures 16 in the inlet extension 9, there are ducts 26having inlets 27 communicating with the bore 28 in the inlet extension 9between the flange 12 and the wall 3. Said ducts are spiraled around theshell 13 toward the end Wall 4 and terminate in open ends 29. The ducts26 are preferably perforated whereby gases passing therethrough mayescape toward the shell 13.

In using a muffier and filter structure as illustrated in FIGS. 2 and 3,with the mufiier inlet connected to an exhaust pipe 10 and the outletreceived in a tailpipe 11 and, with the internal combustion engineoperating, the exhaust gases will be directed through the inletextension 9 into the filter media 15 in the shell 13. A portion of theexhaust gases will bypass said filter, passing into the ducts 26 andescape through the apertures 30 thereof for flow through the space 25into the inlet apertures 17 of the outletextension 9 for dischargethrough the tailpipe 11. The flow of exhaust through the ducts 26 isretarded by the size and length thereof so as to cause the exhaust gasto tend to pass through the filter media 15 to the outlet extension 9'.However, some of the gas will pass through the ducts 26 and be directedthrough small apertures 30 in said ducts which will tend to directparticles into the filter media 15 and the filter media 23, whereby someof the exhaust gas is filtered at all times and the smog-formingelements are reduced.

In the form of the invention illustrated in FIG. 4, the muffler andfilter 31 is substantially the same structure as the mufiier and filterillustrated in FIG. 1 except filter media 23 is arranged around theinterior of the casing 2 and held in place with a perforate cylindricalmember 24 which is illustrated as being a wire mesh. A spiral bafile 32has one end secured to the annular flange 12 at the inlet extension andextends in a spiral in the space between the shell 13 and the perforatemember 24 and terminates as at 34 adjacent the annular flange 12' on theoutlet extension 9 whereby exhaust gases escaping through the valvebypass apertures 16 and are directed in a tortuous passage in the space33 before they reach the apertures 17 to reenter and be dischargedthrough the tailpipe 11. With this arrangement, the bypassed exhaustgases must travel a longer route and in contact with filter elementsboth inwardly and outwardly of the passage to tend to remove additionalcarbon and smog-forming elements. With this addition, the muffler andfilter 31 operate substantially as the structure illustrated in FIG. 1.

It is to be understood that while I have illustrated and describedcertain forms of my invention, it is not to be limited to the specificforms or arrangements of parts herein described and shown except insofaras such limitations are included in the claims.

What I claim and desire to secure by Letters Patent is:

1. An exhaust mufiler filter for internal combustion engines comprising,open-ended inner and outer metal shells in substantially concentricrelation, said shells being radially spaced with a longitudinal passagetherebetween, the outer shell being substantially imperforate and theinner shell being perforate, end walls in said outer shell to close theends thereof, the inner shell being shorter in length than the outershell with the ends of the inner shell adjacent to and spaced from theend walls, an inlet duct extending through one end wall and an outletduct extending through the other end wall, means on inner ends of theinlet and outlet ducts supporting the inner shell, a fibrous filtermedia filling said inner shell between said inlet and outlet ductswhereby exhaust gases moving from the inlet duct to the outlet ductnormally pass through said filter media, said inlet and outlet ductshaving apertures therein between the ends of the inner shell and the endwalls of the outer shell, and valve members on the inlet duct for saidapertures therein and biased into aperture closing position for normallyclosing said apertures against normal operating pressures in the inletduct, said valve members being opened in response to increase ofpressure in the inlet ducts resulting from increase of resistance tofiow through the filter media and thereby permitting flow of exhaustfrom the inlet duct through the passage between the inner and outershells to the outlet duct bypassing the filter media in the inner shell.

2. An exhaust mufiier filter for internal combustion engines comprising,an elongate imperforate casing, end walls closing end portions of saidcasing, atubular duct in one end wall and forming an inlet for exhaustinto said casing, a tubular duct in the other end wall and forming anexhaust outlet from said casing, said inlet and outlet ducts having openends in the casing adjacent said end walls and spaced therefrom, aforaminous. shell extending between said open ends of the ducts anddefining a cross sectional area substantially greater than that of theducts, shell end members mounted on the ducts and extending radiallyoutwardly therefrom and secured to the ends of the shell to support saidshell and form closures for the ends in spaced relation to the end wallsof the casing, said foraminous shell being spaced from the casing todefine a longitudinal passage therebetween in surrounding rela tion tosaid shell, a fibrous filter media filling said foraminous shell for thelength thereof for receiving exhaust gases from the inlet duct whichsaid gases are discharged longitudinally into said filter media, saidoutlet duct having an aperture therein between the adjacent end memberof the foraminous shell and the end wall of the casing for escape ofexhaust gases flowing from the filter media through the foraminous shellinto the longitudinal passage between the shell and casing, and meansoperable in response to increase of pressure in the inlet duct forbypassing a portion of the exahust through the longitudinal passagebetween the casing and shell to the aperture in the outlet duct.

3. An exhaust muifier filter for internal combustion engines comprising,an elongate imperforate casing, end walls closing end portions of saidcasing, a glass fiber mass supported in lining relation to saidimperforate casing, a tubular duct in one end wall and forming an inletfor exhaust into said casing, a tubular duct in the other end wall andforming an exhaust outlet from said casing, said inlet and outlet ductshaving open ends in the casing adjacent said end walls and spacedtherefrom, a foraminous shell extending between said open ends of theducts and defining a cross-sectional area substantially greater thanthat of the ducts, said shell being spaced from the glass fiber masslining said casing to define a passage therebetween, means on said ductsin spaced relation to the end walls and supporting the ends of theforaminous shell and closing said ends between the shell and the ducts,a glass fiber mass filling said foraminous shell for the length thereofwhereby exhaust gases from the inlet duct are discharged longitudinallyinto said glass fiber mass filling said inner shell, means operable inresponse to increase of pressure in the inlet duct for bypassing aportion of the exhaust through the casing between the casing and shellto the outlet duct, and a wall extending from the forarninous shell tothe casing lining and spiraled longitudinally around said forarninousshell to define a spiral passage between said foraminous shell and thecasing lining for the bypassed exhaust gas.

References Cited in the-file of this patent UNITED STATES PATENTS

1. AN EXHAUST MUFFLER FILTER FOR INTERNAL COMBUSTION ENGINES COMPRISING,OPEN-ENDED INNER AND OUTER METAL SHELLS IN SUBSTANTIALLY CONCENTRICRELATION, SAID SHELL BEING RADIALLY SPACED WITH A LONGITUDINAL PASSAGETHEREBYTWEEN, THE OUTER SHELL BEIN SUBSTANTIALLY IMPERFORATE AND THEINNER SHELL EING PERFORATE, END WALLS IN SAID OUTER SHELL TO CLOSE THEENDS THEREOF, THE INNER SHELL BEING SHORTER IN LENGTH THAN THE OUTERSHELL WITH THE ENDS OF THE INNER SHELL ADJACENT TO AND SPACED FROM THEEND WALLS, AN INLET DUCT EXTENDING THROUGH ONE END WALL AND AN OUTLETDUCT EXTENDING THROUGH THE OTHER END WALL, MEANS ON INNER ENDS OF THEINLET AND OUTLET DUCTS SUPPORTING THE INNER SHELL, A FIBROUS FILTERMEDIA FILLING SAID INNER SHELL BETWEEN SAID INLET AND OUTLET DUCTSWHEREBY EXHAUST GASES MOVING FROM THE INLET DUCT TO THE OUTLET DUCTNORMALLY PASS THROUGH SAID FILTER MEDIA, SAID INLET AND OUTLET DUCTSHAVING APERTURES THEREIN BETWEEN THE ENDS OF THE INNER SHELL AND THE ENDWALLS OF THE OUTER SHELL, AND VALVE MEMBERS ON THE INLET DUCT FOR SAIDAPERTURES THEREIN AND BIASED INTO APERTURE CLOSING POSITION FOR NORMALLYCLOSING SAID APERTURES AGAINST NORMAL OPERATING PRESSURES IN THE INLETDUCT, SAID VALVE MEMBERS BEING OPENED IN RESPONSE TO INCREASE OFPRESSURE IN THE INLET DUCTS RESULTING FROM INCREASE OF RESISTANCE TOFLOW THROUGH THE FILTER MEDIA AND THEREBY PERMITTING FLOW OF EXHAUSTFROM THE INLET DUCT THROUGH THE PASSAGE BETWEEN THE INNER AND OUTERSHELLS TO THE OUTLET DUCT BYPASSING THE FILTER MEDIA IN THE INNER SHELL.